Water solution, clean fracturing fluid and method for fracturing reservoir

a technology of clean fracturing fluid and water solution, applied in the field of fracturing, can solve the problems of limited solid carrying capacity, difficult exploitation, low viscosity of fracturing fluid,

Active Publication Date: 2019-04-02
CHINA UNIV OF PETROLEUM (EAST CHINA) +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0005]To overcome the above-mentioned defects in the fracturing fluids in the prior art, the present invention provides a water solution, a clean fracturing fluid, and a method for fracturing reservoir. The water solution provided in the present invention can be introduced with carbon dioxide for gelatinization, and then introduced with air, nitrogen, or an inert gas for gel breaking, so as to realize cyclic utilization of a fracturing fluid, and solve the problems in conventional fracturing fluids used in fracturing stimulation of oil and gas reservoirs, including incomplete gel breaking, severe damages to the reservoir, and severe contamination of the flow-back fluid, etc.
[0010](1.) The water solution described in the present invention can be gelatinized easily, the clean fracturing fluid obtained after gelatinization can be treated with a simple method for complete gel breaking, and the flow-back is easy, so that the water solution can be utilized cyclically easily.
[0011](2.) All of the reagents used in the gelatinization process of the water solution and the gel breaking process of the clean fracturing fluid in the present invention are non-toxic and harmless gasses, which are convenient to use, cheap, and widely available.
[0012](3.) The present invention not only overcomes the drawbacks of the conventional fracturing fluids, including incomplete gel breaking and severe damages to the reservoir, etc., but also solves the problems of high cost of clean fracturing fluid and severe contamination of the flow-back fluid, etc.;
[0013](4.) The present invention can save cost and realize resource exploitation and environmental protection.

Problems solved by technology

As most oil fields enter into a high water-cut stage, the exploitation becomes more and more difficult.
However, slickwater fracturing fluids have low viscosity and limited solid carrying capacity; guanidine gel fracturing fluids may cause severe damages to the reservoirs.
However, for unconventional oil and gas reservoirs, the demand for fracturing fluid and water resource is high owing to great well depth and long horizontal section, and the flow-back fluid generated after fracturing not only involves high treatment cost, but also may result in severe environmental pollution if it is discharged to the external environment.
Moreover, owing to the fact that the molecular structure of slickwater fracturing fluid or guanidine gel fracturing fluid is changed or destroyed after gel breaking, complex chemical and physical treatment is required or a large quantity of original fluid has to be added to the flow-back fluid, before the flow-back fluid can be reused.
Therefore, how to efficiently utilize the large quantity of flow-back fluid is a challenge in efficient fracturing stimulation of unconventional oil and gas reservoirs at present.

Method used

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  • Water solution, clean fracturing fluid and method for fracturing reservoir
  • Water solution, clean fracturing fluid and method for fracturing reservoir
  • Water solution, clean fracturing fluid and method for fracturing reservoir

Examples

Experimental program
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Effect test

example 1

[0047]3 g stearamidopropyl dimethylamine in a white solid form and 0.3 g sodium p-toluenesulfonate are loaded into a beaker filled with 96.7 g water while stirring, the mixture is stirred further for 10 min. at 40° C., and then is kept still, to obtain a water solution (the viscosity of the system is 18 mPa·s), carbon dioxide is introduced into the obtained water solution for 1-2 min. (at a rate of 0.2 L / min.), and then the water solution is sealed and kept still; thus, a clean fracturing fluid A1 (containing 3 wt % stearamidopropyl dimethylamine, 0.3 wt % sodium p-toluenesulfonate, and water (accounting for the remaining content)) is obtained.

example 2

[0048]5 g erucamidopropyl dimethylamine in a white block form and 0.5 g cis-butenedioic acid are loaded into a beaker filled with 94.5 g water while stirring, the mixture is stirred further for 10 min. at 40° C., and then is kept still, to obtain a water solution (the viscosity of the system is 19 mPa·s), carbon dioxide is introduced into the obtained water solution for 1-2 min. (at a rate of 0.2 L / min.), and then the water solution is sealed and kept still; thus, a clean fracturing fluid A2 (containing 5 wt % erucamidopropyl dimethylamine, 0.5 wt % cis-butenedioic acid, and water (accounting for the remaining content)) is obtained.

example 3

[0049]2 g oleamidopropyl dimethylamine in a yellow oil form and 0.2 g sodium salicylate are loaded into a beaker filled with 97.8 g water while stirring, the mixture is stirred further for 10 min. at 40° C., and then is kept still, to obtain a cream-colored water solution (the viscosity of the system is 9 mPa·s), carbon dioxide is introduced into the obtained water solution for 1-2 min. (at a rate of 0.2 L / min.), and then the water solution is sealed and kept still; thus, a clean fracturing fluid A2 (containing 2 wt % oleamidopropyl dimethylamine, 0.2 wt % sodium salicylate, and water (accounting for the remaining content)) is obtained.

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Abstract

The present invention relates to the fracturing field, and discloses a water solution, a clean fracturing fluid, and a method for fracturing reservoir. The water solution contains organic acid amidopropyl dimethylamine, an additive, and water, wherein, the additive is at least one of salicylate, cis-butenedioic acid, o-phthalic acid, dodecyl sulfonate, p-toluene sulfonate, and benzoate. The water solution has high carbon dioxide response performance, a clean fracturing fluid that contains the water solution has superior cyclic utilization performance, and the fracturing fluid can solve the problems of conventional fracturing fluids used in fracturing stimulation of oil and gas reservoirs, including incomplete gel breaking, severe damages to the reservoir, and severe contamination of flow-back fluid, etc.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to Chinese Application No. 201710359670.6, filed on May 19, 2017, entitled “A Recyclable and CO2-Response Clean Fracturing Fluid”, which is specifically and entirely incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates to the fracturing field, in particular to a water solution, a clean fracturing fluid prepared from the water solution, and a method for fracturing a reservoir with the clean fracturing fluid.BACKGROUND OF THE INVENTION[0003]As the oil and gas industry is developed, unconventional gas reservoirs (tight sandstone gas, coal-bed gas, and shale gas) have become a new developing trend of the global low-carbon economy, and their exploration and development has been scaled up gradually. Among proved oil reserves in China, low-permeability oilfields account for one quarter or higher share. As most oil fields enter into a high water-cut stage, the exploitation becomes mo...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C09K8/68C07C233/05C07C57/46C07C57/13C07C57/145C09K8/72C07C309/04
CPCC09K8/68C07C57/13C07C57/145C07C233/05C07C309/04C09K8/72C07C57/46C09K2208/26C09K8/602
Inventor DAI, CAILIZHAO, MINGWEILIU, HEWU, YININGZHAO, GUANGSUN, YONGPENGWU, XUEPENG
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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